Q1: What's new in PPPL Cluster RHEL4 release?
Q2: Why my tcsh shell variable, like PATH, defined in ~/.login got reset in my batch job
    environment?
Q3: I use csh/tcsh shell and my shell setups work fine in RHEL3.  But on RHEL4, I get an
    error message saying:
        "Modules does not appear to be setup correctly.  Please ask your administrator for help."
Q4: I use Lahey/Fujitsu compiler on 32 bit RHEL3.  Any change to LF compiler on RHEL4?


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Q1: What's new in PPPL Cluster RHEL4 release?

A1: From a user point view, there are a few things that are different from RHEL3 clusters:

	1. A user must load ppplcluster module.  It is loaded automatically for a user upon 
	   log into portalr4.  But you might need it if you run qsub in a script or run into
	   any problem.  "module purge; module load ppplcluster" will put you back on track.

	2. MOAB scheduler does enforce memory limits for a running job.  The default is 
	   500,000 KB.  If you need more, use "#PBS -l mem=600mb", for example, in your job 
	   script.

Q2: Why my tcsh shell variable, like PATH, defined in ~/.login got reset in my batch job 
    environment?

A2: The way a shell sources its setup files is based on if it is a login shell or a non-login 
    shell.   ~/.login file is sourced only in login shell start up.  Under PBS, ~/.login
    file is sourced on the head node but not on the rest of compute nodes.  The compute nodes
    source ~/.cshrc only.  This introduces inconsistency in execution environment.  Our system 
    enforces consistency for a batch job on all assigned nodes, including the head node. 

    It is recommanded to set your batch job related shell variables, like PATH and module 
    load, in your ~/.cshrc file. 

    If a user find the need to disable this feature, one may set a flag in the shell setup 
    files as:
	For tcsh:
		setenv USER_ENV_RESET_DISABLED 1
	For bash:
		export USER_ENV_RESET_DISABLED=1
    to disable subsequent resetting by system shell setup file.
 
Q3: I use csh/tcsh shell and my shell setups work fine in RHEL3.  But on RHEL4, I get an 
    error message saying: 
	"Modules does not appear to be setup correctly.  Please ask your administrator for help."

A3: There is a subtle change at system level csh/tcsh shell setup in RHEL4 distribution.  It 
    is recommended that you add following line at the top of your .cshrc file:

	/usr/bin/test -r /etc/profile.d/pppl.csh && source /etc/profile.d/pppl.csh

    This will resolve your module setup issues.

Q4: I use Lahey/Fujitsu compiler on 32 bit RHEL3.  Any change to LF compiler on RHEL4?

A4: The 32 bit Lahey/Fujitsu compiler from RHEL3 does not work on 64 bit RHEL4.  A new 64 bit 
    Lahey/Fujitsu compiler (module lff95/8.00a_64bit) has been installed and set as the default.

    The command is "lfc", instead of "lf95".

    On 64 bit RHEL4, we recommand Pathscale compiler instead of lff95.